Rotary electric switch



Nov. 15, 1949 w. c. FuRNAs ET AL 2,4831%? ROTARY ELECTRIC SWITCH Filed NOV. 26, 194'? 3 SheetsSheet l Aria/awa Nov. 15, 1949 w. c. FuRN ET AL 2,487,967

ROTARY ELECTRIC SWITCH Filed Nov. 26, 1947 3 Sheets-Sheet 2 7 INVENTORS Filed, Nov. 26, 194'? W- FURNAS ET AL,

ROTARY ELECTRIC SWITCH 3 Sheets-Sheet 3 INVENTORS A T'T'QPA/EKS'.

Patented Nov. 15, 1949 ROTARY ELECTRIC swrron William 0. Furnas, Batavia, and Nobel n. Koertge, Glen Ellyn, 111., assignors to Furnas Electric Company, Batavia, 111., a corporation of Illinois Application November 26, B47, Serial No. 788,280

Our present invention relates generally to improvements in apparatus for regulating electric current, and relates more specifically to improvements in the construction and operation of rotary electric tap switches for controlling the voltage applied from one electrical device to another.

The primary object of the present invention is to provide an improved tap switch assemblage which is adapted to establish successive circuits with the taps of a multi-phase transformer or the .like, in regular sequences at each of the phases and in a manner whereby the load is always maintained substantially balanced.

Some of the more specific objects of our invention are as follows:

To provide an improved rotary tap switch wherein a single control handle or manipulator may be utilized to maintain substantial load balance in electrolytic plating and other multiphase electrical systems, by producing regular sequential establishment of successive circuits at each phase.

To provide an improved multiple contact switch for controlling the voltage in poly-phase electrical systems, wherein a plurality of movable contacts are simultaneously operable to automatically maintain desirably balanced load conditions on all of the phases of the system at all times. I

To provide an improved rotary switch in which a multiplicity of movable and fixed contacts cooperate to provide efiective electrical connections, and wherein a number of movable contacts may be shifted in regular sequential order so as to successively engage the successive fixed contacts of a like number of series.

To provide an improved multi-position tap changing switch assemblage, which is simple and compact in construction, flexible in its adaptations, and highly eflicient in operation.

These and other specific objects and advantages of our present invention will be apparent from the following detailed description.

A clear conception of the features constituting the present improvement, and of the mode of constructing and of operating a typical tap switch embodying the invention, may be had by referring to the drawings accompanying and forming a part of this specification in which like reference characters designate the same or similar parts in the various views.

Fig. 1 is a part'sectional side elevation of a typical rotary tap changing switch for threephase electrical systems, involving three movable contacts and three sets each comprising eight stationary contacts;

Fig. 2 is a somewhat reduced front and side perspective view of the switch assemblage of Fig. 1;

Fig. 3 is a front view of the rotary tap switch 7 Claims. (Cl. 200-11) drawn to the scale of Fig. 1, but with the manipulating handle omitted;

Fig. 4 is another somewhat reduced rear and side perspective view of the same rotary switch assembly;

Fig. 5 is a transverse section through the switch taken along the line 5-5 of Fig. 1, and drawn to the same scale;

Fig. 6 is a typical wiring diagram of an electrolytic plating system showing the improved voltage control switch applied; and

Fig. 7 is a plan view of one of the movable contact sectors of. the new switch.

While our invention has been shown and described herein as being advantageously applicable to a rotary tap switch for controlling the voltage applied from a multiple tap three-phase transformer to .a rectifier unit used for electrolytic plating, it is not our desire or intention to limit the scope or the utility of the improved features by virtue of this restricted disclosure; since these switches provided with more or less contacts may also be utilized for diverse other purposes such as for voltage control on the wound rotors of A.-C. motors for secondary speed control.

Referring to the drawings, the typical rotary tap switch shown therein by way of illustration, comprises in general three similar parallel and coaxial insulating rings 10, ll, 12 each having a series of eight radially disposed stationary contact l4 mounted thereon and projecting inwardly therefrom; front and rear end panels or plates l5, l5 respectively rigidly united by bolts i1 piercing the rings H], H, l2 and provided with spacer tubes 18 for definitely locating these rings relative to the interconnected end plates; apolygonal shaft or spindle l9 having cylindrical opposite ends journalled for rotation in bearings 20, 2| carried by the panels l5, [6 respectively, and having a manipulating handle 22 adjustably and detachably secured to its forward extreme end by means of a fastening screw 24; three laterally spaced movable contact sectors 25, 26, 2'! carried by and coacting with the spindle l9 through an insulating bushing 28, and each being cooperable respectively with the successive fixed contacts 14 of the insulating rings 10, ii, l2, these movablesectors also being in constant contact with the hubs of adjacent bus bars 30, 31, 32 respectively having hub rings 33 surrounding spacer sleeves 34, and fixedly secured to the corresponding rings I0, ll, l2 by connector bolts or screws 35; and indexing and holding mechanism associated with the back of the front plate l5 and coacting with the spindle I9 between this plate and the ring ill to maintain the rotor in various positions of adjustment.

The insulating rings [0, ll, l2 are preferably sturdily constructed of electrical insulating material, and with U-shaped transverse cross-section, and cooperate with the end plates I5, I6 and with the four bolts I1 and spacers I8 to provide a rigid cage-like frame within which the polygonal spindle I9 is centrally rotatably confined. The fixed contacts I4 may be firmly secured to their respective carrier rings III, II, I2 by means of connector screws or bolts 36, and each of these bolts 36, as well as the screws 35, is provided with a terminal attaching nut 31. The spindle I9 may be square or otherwise polygonal between its cylindrical end bearing portions, and the square medial portion of this spindle is snugly embraced throughout its length by the insulating bushing 28 while the latter is surrounded by the spacer sleeves 34 which contact the bushing corners and are also formed of electrical insulating material, see Fig. 5. The outer face of the front plate I may be provided with suitable calibrations and indicia, not shown, designating the various switch settings, and the manipulating handle 22 may be adjusted and fixed to the spindle I9 in any desired angular position, with the aidof the attaching and clamping screw 24.

The movable contacts besides embodying the sections 25, 26, 21 each snugly laterally engaging the hub ring 33 of an adjacent bus bar 30, 3|, 32, also comprise spring sector plates 38, as shown in Figs. 1, 4 and 5. Each of the movable contact sectors 25, 26, 21 is constructed as illustrated in Fig. 7 of sheet metal and with an integral hub ring provided with a polygonal opening 39 adapted to snugly receive and engage the correspondingly polygonal bushing 28, thereby providing a positive driving connection between the rotary spindle I9 and each movable contact. The spacer sleeves 34 engage the opposite sides of the sectors 25, 26, 21 and thus prevent displacement of the movable contacts along the spindle I9,and these sleeves 34 are forced into clamping engagement with the integral hub rings of the sectors by means of a nut 40 coacting with screw threads on the spindle, as shown in Figs. 1 and 4. The polygonal openings 39 of the successive sectors 25, 26, 21 are disposed at different angles relative to the spindle axis so as to cause the three movable contacts to be staggered relative to each other as depicted in Figs. 3, 4 and 5, and the fan shaped revolving outer ends of the resilient sectors 25, 26,

the front panel I5 of the assemblage.

21 are adapted to snugly coact with the front faces of the successive adjacent fixed contacts I4 as shown in Fig. 1.

In order to insure snug coaction between th fixed and movable contacts and between the latter and the adjacent bus bars 30, 3i, 32, a sheetmetal spring sector plate 38 is provided adjacent to each of the sectors 25, 26, 21 and is caused to coact with the rear faces of the adjacent bus bar and fixed contacts I4. Each movable contact sector has an integral lip 42 projecting rearwardly therefrom and coacting with an opening 43 formed in the adjacent spring plate 38, and each sector 25, 26, 21 is also provided with a local hump 44 adapted to engage the mid-portion of the corresponding plate 38, as shown in Fig. 1. Each of the sectors and the adjacent spring plate, are also pierced by a headed pin 45 carrying a washer 46 at its rear end, and a helical compression spring 41 surrounds each pin 45 between the washer 46 and the adjacent plate 38. The inner end of each spring plate 38 is U-shaped and coacts with the exterior of an adjacent spindle sleeve 34, and the springs 41 tend to constantly force the plates 38 toward the corresponding contact sectors 25, 26, 21 and the adjacent bus bar hub rings 33 against these sectors, while also urging the outer extrem- 4. ities of the movable sectors against the fixed contacts I4, thereby insuring effective electrical connections between the movable contacts and the fixed bus bars and the active fixed contacts I4. at all times.

The rotor comprising the spindle I9, movable contacts, and the manipulating handle 22, is rotatable step by step so as to progressively advance the sectors 25, 26, 21, and in order to insure advancement of the movable contacts by equal well defined steps, the rotor is provided with accurate indexing mechanism associated with the rear of This mechanism consists primarily of a peripherally notched indexing wheel or cam 49 secured to the square medial portion of the spindle I9 near the panel plate I5 and having thereon a forwardly extending stop lug 56 which is cooperable with a similar lug 5I carried by the panel I5; a pair of diametrically opposite rollers 52, 53 carried by the medial portions of levers 54, 55 respectively, which are swingably suspended by pivots 56, from the rear of the outer panel plate I5; and a helical tension spring 51 interconnecting the swinging ends of the levers 54, 55 so as to constantly urge the rollers 52, 53 toward the notches 58 in the periphery of the cam wheel 49. The stop lugs 58, 5| are obviously cooperable with each other to prevent more than one complete revolution of the movable contacts, and the notches 58 of the indexing cam 49 should be uniformly spaced and formed so as to produce well defined steps of advancement of the desired magnitude whenever the movable contact carrying rotor is revolved and to hold this rotor in various positions of adjustment.

When the tap switch unit has been constructed and assembled as hereinabove described, it may be utilized for various purposes, and as shown in the typical wiring diagram of Fig. 6, the switch assembly has been installed to control the voltage applied from a multiple tap three-phase transformer 6| to a rectifier unit 60 used for electrolytic plating. The installation depicted provides for twenty-two different settings produced by utilizing a corresponding number of active notches 58 of the indexing cam 49, and whenever the manipulating handle 22 is displaced one position or notch spacing, only one of the movable contact sectors 25, 26, 21 will be advanced to engage a new or previously unengaged fixed contact I4. While this new engagement or circuit closin is being effected, th other two movable contact sectors 25, 26, 21 remain in engagement with the same fixed contacts I4 which they had previously contacted. This result is accomplished by havin the movable sectors 25, 26, 21 relatively wide and staggered, while the fixed contacts I4 of the several series are relatively narrow and not staggered. When the handle 22 and rotor are subsequently displaced a distance corresponding to another notch spacing, another movable sector 25,16, 21 engages a new fixed contact I4 while the two remaining sectors remain in engagement with their previously engaged contacts I4; and during each successive movement of the handle 22 new circuits are established with the various transformer taps in regular sequence in each of the three phases so that the load is always substantially balanced.

Perhaps a clearer conception of the operation and functioning of the improved tap switch, may be had by referring to Fig. 5 wherein all three of the movable contact sectors 25, 26, 21 are shown in engagement with the upper-most fixed contacts I to the left of the central plane or axis of the switch. when the manipulating handle 22 is moved in a counter clockwise direction as viewed in Fig. 5, so as to cause the holding rollers 52, 53 to engage the next pair of diametrically opposite notches 58 of the cam wheel 49, the leading contact sector 25 will engage the next lower fixed contact I! of its series, but the sectors 26, 21 will remain in engagement with the adjacent uppermost fixed contact 14 at the left of the central vertical plane of the switch.

As the three sectors 25, 26, 21 are subsequently advanced a step farther, the two outermost sectors 25, 21 will remain in engagement with their previously engaged fixed contacts H, while the intermediate sector 26 will be brought into engagement with its next lower stationary contact l4. When the three movable contact sectors 25, 26, 21 are thereafter advanced still another step, the movable sectors 25, 26 will remain in engagement with said next lower contacts it while the sector 21 will be brought into engagement with the next succeeding lower fixed contact H of its corresponding series located directly beneath the horizontal central plane of the assemblage.

maintain two of the sectors 25, 26, 21 in engagement with the previously engaged fixed contacts ll of their series, while the third sector is always brought into engagement with a new stationary contact ll of its series; and the spring 51 coacts with the levers 54, 55 and with the rollers 52, 53 to positively retain the parts in the successive positions of adjustment.

The rotor of the switch may obviously be revolved in one direction to produce a series of twenty two successive different positions, and may also be reversed to repeat the sequence of the settings in reverse order. The same principle of operation may however be embodied in a tap switch having more or less available positions of setting, by merely varying the widths of the movable contact sectors, the spacing and the number offixed contacts, and the step magnitude of the indexing mechanism. The formation of the movable contacts each comprising a sector 25, 26, 21 and a cooperatin spring plate 38, is such that each sector and plate will snugly engage the opposite sides of each intervening fixed contact l4, and the compression springs 41 coacting with the spring plates 38 also insure snug engagement between the hubs of the sectors 25, 26, 21 and the adjacent bus bar hub rings 33 at all times. The indexing mechanism also serves to advance the movable contacts with a desirable snap action, besides firmly holding the rotor in various pre-set positions; and the staggerin of the movable contacts is of importance in order to produce the desired sequential positions.

From the foregoing detailed description it should be apparent that our present invention provides a simple and compact tap switch unit which may be manipulated with the aid of a single handle 22 or the like, to produce a regular sequence of tap connections at each phase so as to maintain the load substantially balanced at all times. The various parts of the improved assemblage may be readily constructed, most of them from sheet and tube stock, to provide a durable switch, all elements of which may be readily assembled and dismantled while being accessible for convenient inspection at all times. The rotor assemblage and its indexing mechanism are well confined and protected by a sturdy cage-like The movable contacts may then be advanced step by step to constantly frame which may be mounted in any desired manner upon a suitable support, and the improved switch unit is highly flexible in its adaptations and may be effectively utilized for diverse purposes. The cost of production of the switch is also reduced to a minimum by making various similar parts of the assemblage interchangeable with each other, and the several sections of the switch mechanism are also well insulated from each other. The invention has proven highly satisfactory and successful in actual use especially in connection with systems such as specifically shown and described herein, and the switch units may be manufactured, sold, and operated at moderate cost since few parts are subjected to excessive wear.

It should be understood that it is not desired to limit this'invention to the exact details of construction or to the precise mode of use, herein shown and described, for various modifications within the scope of the appended claims may occur to persons skilled in the art; and it is also contemplated that specific descriptive terms employed herein be given the broadest possible interpretation consistent with the disclosure.

We claim:

1. A rotary switch comprising, a frame, three coaxial annular series of axially alined fixed contacts carried by said frame, a rotor journalled in said frame and having thereon a radial movable contact successively cooperable with the fixed contacts of each of said series, said movable contacts overlapping each other circumferentially but being staggered and revolvable step by step so that two of the movable contacts will always remain in engagement with the same fixed contacts whenever the third movable contact is being advanced into engagement with a new fixed contact and the fixed contacts being so spaced that only one at a time is re-engaged during each step advancement of the rotor, and a single manipulator for revolving said rotor to simultaneously advance all of said movable contacts.

-2. A rotary switch comprising, a frame, at least three coaxial annular series of radial axially alined fixed contacts carried by said frame, a rotor journalled in said frame and having thereon radial sector-shaped movable contacts successively cooperable with the fixed contacts of each of said series, said movable sector-shaped contacts overlapping each other circumferentially but being progressively staggered and revolvable step by step so that two of the movable contacts always remain in engagement with the same fixed contacts whenever a third movable contact is being advanced into engagement with its next fixed contact and said fixed contacts being so spaced that only one at a time is re-engaged by the sectors while each sector is wide enough to engage one fixed contact in the step which separates it from the last fixed contact of the same series, and means for revolving said rotor to simultaneously advance the movable contacts.

3. A rotary switch comprising, a frame, an annular series of fixed contacts carried by said frame, a rotary spindle journalled in said frame and having a polygonal medial portion, and a movable contact radiating from said spindle and being revolvable thereby to engage the successive fixed contacts of said series, said movable contact including a contact sector having an inner portion completely surrounding and snugly embracing said polygonal spindle portion and a sector plate having an outer portion constantly resiliently 7 urged toward said contact sector and having it inner portion formed U-shaped to only partially surround the spindle.

4. A rotary switch comprising, a frame, an annular series of fixed contacts carried by said frame, a rotary spindle journalled in said frame and having a polygonal medial portion, and a movable contact radiating from said spindle and being revolvable thereby to engage the successive fixed contacts of said series, said movable contact including a contact sector provided with an inner portion embracing and fixed against movement relative to said polygonal spindle portion and a sector plate resiliently urged toward said contact sector and having its inner portion only partially and loosely surrounding the spindle and movable therealong.

5. A rotary switch comprising, a frame, an annular series of fixed contacts carried by said frame, a rotary spindle journalled in said frame and having a polygonal medial portion, and a movable contact radiating from said spindle and being revolvable thereby to engage the successive fixed contacts of said series, said movable contact including a contact sector provided with an inner portion embracing and fixed against movement relative to said polygonal spindle portion and a sector plate resiliently urged toward said contact sector and having its inner portion only partially and loosely surrounding the spindle and movable therealong, a headed pin coacting with said contact sector and piercing said sector plate, and a spring surrounding said pin and coacting therewith and with'said plate to urge the latter toward said sector.

6. A rotary switch comprising, a frame, three coaxial annular series of equally spaced radial fixed contacts having the corresponding contacts sively staggered and revolvable step by step so that two movable contact sectors always remain in engagement with the same fixed contact whenever the third sector is advanced into engagement with its next fixed contact and said fixed contacts being spaced apart so that only one at a time is re-engaged by the adjacent sector, and means for imparting step by step revolving motion to said rotor.

7. A rotary switch comprising, a frame, three coaxial annular series of equally spaced radial fixed contacts having the corresponding contacts of all series axially alined and carried by said frame, a rotor journalled in said frame and having thereon radial movable contact sectors successively cooperable with the fixed contacts of adjacent series and of a width sufiicient to engage one fixed contact of the adjacent series whenever separated from another fixed contact of the same series, said contact sectors being progressively staggered and revolvable step by step so that two movable contact sectors always remain in engagement with the same fixed contact whenever the third sector is advanced into engagement with its next fixed contact and said fixed contacts being spaced apart so that only one at a time is re-engaged by the adjacent sector, means for revolving said rotor to simultaneously advance said sectors, and means for limiting advancement of the rotor to steps of less magnitude than the spacing distances between said fixed contacts.

WILLIAM C. FURNAS. NOBEL H. KOERTGE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

